To improve the throughput of cells and conduct interference coordination among cells, a COordinate MultiPoint (COMP) transmission and reception technology of network level is introduced into new-generation wireless communication systems such as the LTE-Advance system and an International Mobile Telecommunication Advance (IMT-Advance) system.
In the 56th 3GPP LTE Conference, two types of reference signals of the LTE-Advanced have been defined: Channel State Information Reference Signal (CSI-RS for short) and DeModulation reference signal (DMRS for short); the former is used for channel measurement and the latter is used for demodulation. Therefore, the common reference signal of LTE is only overhead for LTE-A users, rather than brings additional gain.
If LTE-A dedicated resource is defined, by not transmitting the common reference signals or transmitting part of them, the performance of the LTE-A system can be improved.